.NET Component - Error when using Late Binding

Using Visual Studio 2008 I've built a COM object that targets the .Net Framework 2.0.

I'm trying to use the component in MS Access 2开发者_JS百科007 on XP SP3. If I use early binding it works flawlessly. If I use late binding I get this error:

Run-time error '429':
ActiveX component can't create object

Here's my code:

Dim objTest as Object
Set objTest = CreateObject("MyComNameSpace.MyComClass") 'Error occurs here

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Well, looks like the ProgId isn't "MyComNameSpace.MyComClass". Look in the registry with Regedit.exe, it should be present in HKEY_CLASSES_ROOT. The key contains a CLSID key with a guid for your class. That key should be present in HKLM\Software\Classes\CLSID\{guid}. Which contains keys written by Regasm.exe to get the CLR started and your assembly loaded.

You can see these keys being searched by the COM client program with SysInternals' ProcMon utility, a decent way to diagnose what's missing.

You can use the [ProgId] attribute to pick your own instead of letting the it up to .NET to pick one.

Just in case, just because you use late-binding does not mean that you can skip the registration step. Be sure to run Regasm.exe with the /codebase option from an elevated command prompt to get the keys registered.